32 THEORIES 



but unlike the latter in this, that the germs are not repro- 

 duced by the organism of the sick, but exteriorly to, and 

 independently of, the human body. In other words, that 

 as the germs of contagious diseases are reproduced in 

 the body, the germs productive of malarious and other 

 non-contagious diseases are elaborated and re-elaborated 

 out of the body, and independently of its agency. One 

 is the product of person, the other of place. This notion 

 is sustained by the fact that organic azotized substances 

 are the only things detected in marsh air or dew, which 

 can possibly affect the health injuriously. 



Although I approve of the reference of malarious dis- 

 eases to the causation by organic germs, I am far from 

 being satisfied with the animalcular direction taken by all 

 who have elaborated a theory on this foundation. Hither- 

 to it has been so feebly sustained by proofs, as to have 

 at no time received general favor from the profession, 

 although supported by some eminent men in almost every 

 period of medical history. The chief objections to the 

 animalcular theory are: 1st. That it has never been shown 

 that animalcules are poisonous in any way. 2d. That 

 none of the difficulties of this puzzling subject are thus re- 

 moved. 3d. That the assumption is hypothetical at first, 

 and does not in the progress of an examination become at 

 any time more demonstratively probable, or logically 

 acceptable. 4th. But the strongest objection is founded 

 on the superior probability of the vegetable branch of the 

 organic theory, by which I hope to show that very much 

 of the obscurity of this subject may be dissipated. This 

 last objection will, as we advance, rise into more remark- 

 able prominency. 



It is painful to be thus compelled to abandon the inge- 

 nious theories of our fathers, built up so elaborately and so 



